This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Obesity is a heritable trait and a major risk factor for highly prevalent common diseases such as hypertension, cardiac diseases and type 2 diabetes. Obesity is a major public health concern worldwide. Previously we showed that BMI was positively correlated with African ancestry among the African American (AA) participants in the NHLBI's Family Blood Pressure Program (FBPP). Using Individual Ancestry (IA) estimates at 284 marker locations across the genome, we now present a Quantitative Admixture Mapping (QAM) analysis of body mass index (BMI) in the same population. We used a set of unrelated individuals from Nigeria to represent the African ancestral population and the European Americans in the FBPP as the European ancestral population. The analysis was based on a common set of 284 microsatellite markers genotyped in all three groups. We considered the quantitative trait, BMI, as the response variable in a regression analysis, with the marker location specific excess of European ancestry as the explanatory variable. After suitably adjusting for different covariates such as sex, age and study center, we found strong evidence for a positive association with European ancestry at chromosome locations 3q29 and 5q14 and a negative association on chromosome 15q26. These results suggest that these regions may harbor genes influencing BMI in the AA population.